Textile, hot-melt (fusion) adhesives based on linear, saturated, high-molecular weight copolyesters are known. However, the heretofore available products exhibit certain disadvantages which restrict their practical applicability in specific working areas.
Thus, DOS No. 1,920,432 describes copolyesters of terephthalic acid, adipic acid, ethylene glycol, and 1,4-butanediol. However, the softening points of these copolyesters (&gt;130.degree. C.) are too high for use as heat-sensitive materials; alternatively, the copolyesters having a low softening point (&lt;130.degree. C.), due to their low crystallinity, exhibit such a tackiness even at room temperature that they are unsuitable for use as pulverulent hot-melt adhesives. Moreover, the dry cleaning stability of these copolyesters leaves much to be desired.
DAS No. 2,435,863 discloses copolyesters of terephthalic acid, isophthalic acid and/or an aliphatic dicarboxylic acid and 1,4-butanediol/1,6-hexanediol mixtures as the diol component. These copolyesters are characterized, inter alia, by melting points of &gt;40.degree. C., which are too low. The degree of crystallization of these copolyesters is indeed slightly higher than in those products mentioned in DOS No. 1,920,432. However, the crystallizing velocity of the resultant granulated material obtained under practical conditions is so low that technical disturbances occur due to agglomeration during grinding of the granules and classification of the powder (U.S. Pat. No. 4,217,426); also, the shelf stability of such powders is low due to caking. During processing, the pressure rolls of the powder point machines frequently become gummed up.
To avoid the aforementioned drawbacks, U.S. Pat. No. 4,217,426 proposes blending copolyesters with low-viscosity polyethylene waxes. The blending represents an additional process step. Moreover, the compatibility of the polyethylene waxes with the copolyesters is so minor that even at low concentrations of the polyethylene wax, a brittle, frangible material is obtained.